William I. Norwood

Physiologic repair of aortic atresia-hypoplastic left heart syndrome.

AORTIC-VALVE atresia associated with mitral atresia or stenosis, a diminutive or absent left ventricle, and severe hypoplasia of the ascending aorta and aortic arch make up a constellation of defec...

Hypoplastic left heart syndrome: Experience with palliative surgery

Aortic atresia is a form of hypoplastic left heart syndrome always complicated by associated severe hypoplasia of the ascending aorta and various degrees of mitral valve and left ventricular hypoplasia. At present it is a universally fatal lesion in early infancy. This is a report of a new palliative procedure for hypoplastic left heart syndrome that has resul;ed in early ongoing survival of two infants with aortic atresia. On the basis of experience with a third patient, an operation for future physiologic correction is proposed.

Transposition of the Great Arteries and Intact Ventricular Septum: Anatomical Repair in the Neonate

Fourteen neonates 18 hours to 32 days old with transposition of the great arteries (TGA) and virtually intact ventricular septum (IVS) underwent arterial switch operations under deep hypothermic circulatory arrest. Preoperative left ventricular to right ventricular peak systolic pressure ratios ranged from 0.7 to 1.0 (mean, 0.92), and the echocardiogram showed a centrally positioned ventricular septum in 10 patients and a rightward displaced ventricular septum in 4. One patient died twelve hours after operation. Postoperative complications included bleeding from the left coronary artery-pulmonary artery anastomosis (1 patient), stenosis of the pulmonary artery-aorta anastomosis requiring reoperation (2 patients), transient ST segment and T wave abnormalities consistent with ischemia (3), and development of pathological Q waves suggestive of clinically silent infarction (2). The capacity of the left ventricle in a neonate to effectively take over the systemic circulation was clearly demonstrated. A longer follow-up period is needed to assess late ventricular function, coronary ostial growth, growth of the aorta-pulmonary artery anastomosis, late aortic valve (anatomical pulmonary valve) function before definitive recommendations about the superiority of the arterial switch operation in neonates with TGA plus IVS can be formulated.

Right Ventricle to Pulmonary Artery Conduit Improves Outcome After Stage I Norwood for Hypoplastic Left Heart Syndrome

Background—Diastolic run off into the pulmonary circulation and labile coronary perfusion are thought to contribute to morbidity and mortality after the Norwood procedure (NP). We compared outcomes from the use of a RV to PA conduit (RV/PA) or a modified Blalock-Taussig shunt (BTS), physiologically distinct sources of pulmonary blood flow. Methods and Results—Review of 56 consecutive patients who underwent a Norwood procedure with a RV/PA (n=36) or a BTS (n=20) between 2000 and 2002. Median age was 4.5 days (range 1 to 40) and median weight was 3.1 kg (range 1.8 to 4.1). The RV/PA was constructed with a 5-mm conduit. Patients in the BTS group received a 4-mm shunt. Comparisons between RV/PA and BTS groups showed no difference for weight, gestational age, prenatal diagnosis, HLHS variant, associated diagnoses, ascending aortic size, ventricular function, AV valve function, and pulmonary venous obstruction. Operative survival was higher with RV/PA [33/36 (92%) versus 14/20 (70%); P =0.05]. Patients with RV/PA had less need for ventilatory manipulations to balance the Qp/Qs (1/36 v/s 8/20; P =0.001), delayed sternal closure (6/36 v/s 7/20; P =0.001), and extracorporeal support (5/36 v/s 7/20; P =0.036). RV/PA patients had more favorable postoperative hemodynamics: higher diastolic blood pressure without changes in systolic blood pressure at 1, 8, 24, 48 hours after the NP (46.3 v/s 39.5; 47.2 v/s 42.1; 46.1 v/s 37.1; and 47.1 v/s 40.2; all P =0.001). Conclusion—RV/PA simplifies postoperative management and improves hospital survival after NP for HLHS.

Use of Hancock porcine xenografts in children and adolescents

Between January 1,1974 and December 31,1978,47 xenografts (8 aortic, 28 mitral, 4 tricuspid, 3 left atrioventricular valve in I-transposition of the great arteries and 3 aortic-mitral) were implanted in 44 patients, aged 10/12 to 20 5/12 years (median 12 2/12). All eight patients with aortic valve replacement survived and were followed up for 22.5 ± 10.4 months (mean ± standard error of the mean). At postoperative cardiac catheterization in three patients, the peak systolic ejection gradient ranged between 24 and 38 mm Hg and the valve area index between 0.71 and 1.15 cm2/m2. Among 26 patients who underwent mitral valve replacement, 5 died operatively and 2 died 2 months postoperatively, leaving 19 long-term survivors who were followed up for 26.2 ± 15.6 months. In the 11 patients who underwent postoperative cardiac catheterization, the mean diastolic gradient was 6.1 ± 2.7 mm Hg and the mean valve index 1.79 ± 0.76 cm2/m2. Severe subaortic obstruction, due to the prosthetic mitral valve, occurred in three of five patients less than 5 years old. n nAmong four patients who underwent tricuspid valve replacement there were no operative deaths; complete heart block occurred in three. At postoperative catheterization in two patients, the mean diastolic gradient was 3 and 5 mm Hg, and the valve index 1.32 and 1.7 cm2/m2, respectively. Three patients with I-transposition of the great arteries who underwent replacement of the systemic atrioventricular valve were followed up for 12 to 37 months. At postoperative catheterization the mean diastolic gradient was 0 to 4 mm Hg and the valve index ranged from 1.68 to 1.88 cm2/m2. Both aortic and mitral valves were replaced in three children. One died at operation and one 6 months after operation. The survivor has complete heart block but is in New York Heart Association functional class I. n nEight xenografts (6 mitral, 1 left atrioventricular valve in I-transposition of the great arteries and 1 aortic) failed, requiring replacement 22 to 68 months after implantation. All were calcified to varying degrees. Valve failure began presenting 22 months after implantation, and of 25 valves implanted for 20 months or longer, 8 have been replaced. These 8 patients were younger (10.3 ± 0.2 years) at initial valve replacement than the other 17 patients (15.0 ± 0.3 years) followed up for 20 months or longer (p <0.05). High levels of γ-carboxyglutamic acid (GLA), a calciumbinding amino acid, were found in all six calcified xenografts analyzed, whereas none was found in a fresh porcine aortic valve or in an unimplanted xenograft. GLA-containing protein, laid down after implantation, may play a role in xenograft calcification.

Early reduction of the volume work of the single ventricle: The hemi-fontan operation

BACKGROUNDnIn hearts with a functional single ventricle, cavity volume and myocardial muscle mass increase as a consequence of the excessive volume work associated with parallel pulmonary and systemic circulations. The hemi-Fontan operation was conceived as a means of accomplishing early reduction of the volume work of the single ventricle.nnnMETHODSnAll patients presenting in infancy with single-ventricle physiology were managed by early hemi-Fontan operation in anticipation of a subsequent completion Fontan operation. Between May 1989 and August 1995, 400 patients less than 2 years of age underwent hemi-Fontan operations. Mean age at operation was 8.5 months (range, 2 months to 24 months). The hemi-Fontan operation included association of superior vena(e) cava(e) with the branch pulmonary arteries, augmentation of the central pulmonary arteries, occlusion of the inflow of the superior vena cava into the right atrium, and elimination of other sources of pulmonary blood flow.nnnRESULTSnOperative mortality ( < 30 days) was 31 of 400 patients (7.8%). For the last 200 patients, operative mortality was 8 of 200 (4.0%). Younger age at operation was not an independent risk factor for operative mortality. Urgent operation in the presence of a hemodynamic burden requiring concomitant procedures was associated with increased mortality.nnnCONCLUSIONSnThe hemi-Fontan operation can be accomplished with low operative mortality in young patients, achieving early reduction of the volume work of the single-ventricle heart.

The significance of tricuspid regurgitation in hypoplastic left-heart syndrome.

Palliation of hypoplastic left-heart syndrome involves use of the morphologic right ventricle as the systemic ventricle and the tricuspid valve (in cases of mitral atresia/stenosis) or the common atrioventricular valve (in cases of malaligned atrioventricular canal) as the systemic atrioventricular valve. To determine the relationship between tricuspid or common atrioventricular valve function and the ultimate outcome of palliative surgery, 100 patients with hypoplastic left-heart syndrome were evaluated preoperatively by Doppler echocardiography to determine the degree of tricuspid regurgitation. These patients were then followed serially to assess changes with time in the functional status of the tricuspid or common atrioventricular valve and to determine the correlation of tricuspid or common atrioventricular valve regurgitation with survival. We discovered that tricuspid or common atrioventricular valve regurgitation is common in hypoplastic left-heart syndrome. Thirty-seven percent of the patients had mild, 13% had moderate, and 3% had severe tricuspid or common atrioventricular valve regurgitation on their preoperative Doppler echocardiograms. Throughout the first 2 postoperative years most patients had no significant change in the degree of tricuspid or common atrioventricular valve regurgitation when findings were compared to those of the preoperative echocardiogram. Patients with moderate or severe tricuspid or common atrioventricular valve regurgitation preoperatively had a significant reduction in their survival when contrasted with patients with no or mild atrioventricular valve regurgitation. We therefore conclude that tricuspid or common atrioventricular valve competence is a significant factor in long-term survival after palliative surgery for hypoplastic left-heart syndrome. This function, however, appears to be unaffected by palliation and remains relatively constant over the first 2 postoperative years.

The hemodynamic effects of dopamine in infants after corrective cardiac surgery.

The hemodynamic effects of dopamine were measured during the immediate postoperative period in five infants with low cardiac output following repair of congenital cardiac defects. Dopamine was administered at doses of 5, 10, 15, 20 and 25 micrograms/kg/minute. Heart rate, systemic arterial pressure, and cardiac index increased significantly at a dose of 15 micrograms/kg/minute or greater. There were no significant changes in right atrial pressure, left atrial pressure, pulmonary artery pressure, pulmonary vascular resistance, systemic vascular resistance, or stroke volume. These data support the hypothesis that inants respond to dopamine in a fashion qualitatively and quantitatively different from that in adults.

Clinical and hemodynamic results of the Fontan operation for tricuspid atresia

Thirty patients aged 3 months to 26 years (median 9 years) with tricuspid atresia or severe tricuspid stenosis underwent a modified Fontan operation at Childrens Hospital, Boston, between 1973 and 1980. Thirty-six palliative operations had been performed previously in 20 patients. Preoperative hemodynamic measurements included: mean pulmonary arterial pressure 6 to 18 mm Hg (median 9); pulmonary vascular resistance 0.3 to 2.2 Woods units/m2 (median 1.5) and left ventricular end-diastolic pressure 3 to 14 mm Hg (median 7). n nThere were five hospital deaths (17 percent), including two in the last 24 operations. The 25 survivors have been followed up for 4 to 85 months (median 23) with no late deaths. Twenty patients are in New York Heart Association class I and four in class II; one infant was not classified. Two patients have required reoperation, at, respectively, 71 and 26 months postoperatively; the former for late-developing conduit obstruction and residual bidirectional shunting; and the latter for a residual right to left shunt at atrial level. Early postoperative monitoring of hemodynamics in the intensive care unit revealed that a mean right atrial pressure of 17 mm Hg or greater, without obstruction of the anastomosis, was invariably associated with serious morbidity or mortality. n nFifteen patients underwent elective cardiac catheterization 9 to 21 months (median 13) postoperatively. The mean right atrial pressure ranged between 5 and 12 mm Hg (median 8) and mean pulmonary arterial pressure between 4 and 11 mm Hg (median 7). The cardiac index (measured in 12 patients) was 1.9 to 4.0 liters/min per m2 (median 3.2). The left ventricular ejection fraction measured in 11 patients did not change significantly postoperatively, remaining normal in 10. Three patients had a residual right to left shunt at atrial level while the arterial oxygen saturation in the remaining 12 patients was 93 to 97 percent. Thus the modified Fontan operation can be performed with excellent clinical and hemodynamic results in selected patients with tricuspid atresia.

Primary surgical closure of ventricular septal defect in the first year of life: results in 128 infants.

Between January 1973 and July 1981, 128 patients less than 1 year of age with failure to thrive, congestive heart failure or pulmonary artery hypertension underwent primary repair of a ventricular septal defect. The hospital mortality rate was 7.8% (10 of 128), and the late mortality rate was 2.3% (3 of 128). Mortality was highest among younger infants with preexisting respiratory problems or a hemodynamically significant residual lesion postoperatively. Complications included a large residual shunt in eight (6.2%), transient neurologic problems in five (3.9%) and persistent complete heart block in three (2.3%). Lung biopsy specimens obtained from 49 patients showed pulmonary vascular abnormalities in all. Complete right bundle branch block developed in 74 (64%) and bifascicular block appeared in 11 (9%). Recatheterization in 70 patients (55%) showed normal pulmonary artery pressures in all but 2 patients with a large residual shunt. Complete closure of the defect had been achieved in 49 (70%), and a hemodynamically insignificant shunt remained in 19 (27%). Patients without significant hemodynamic residua were asymptomatic and tended to accelerate in growth after surgery.